Patent Literature 1 reports an oxazole compound that exhibits a specific inhibitory activity against phosphodiesterase 4 (PDE4). Patent Literature 1 discloses a method for producing an oxazole compound. It indicates, as a typical method thereof, Reaction Scheme 1 to Reaction Scheme 12.
Among these, Reaction Scheme 10 discloses that compound (14) having an oxazole ring is produced by reacting dihaloketone compound (12) (specifically, 1,3-dichloro-2-propanone) with amide compound (13); and that primary amine compound (5a) is produced by reacting compound (16) having a phthalimide group with hydrazine (17).
However, because the starting material dihaloketone compound (12) exhibits strong stimulant and tearing properties; and, furthermore, because hydrazine (17) has a risk of explosion during the processes of concentration and dehydration, it is preferable to avoid the use thereof for the health and safety of the people involved in its production.
Furthermore, in the method for producing the oxazole compound disclosed in Patent Literature 1, purification by column chromatography is necessary in a plurality of processes, in addition to the processes in the above-mentioned Reaction Scheme 10.
However, in order to produce the target product on an industrial scale, a simple and effective production process in which expensive and complicated column chromatography is unnecessary throughout the process is required.